Paper by Erik D. Demaine

We introduce a new data structuring paradigm in which operations can
be performed on a data structure not only in the present but also in
the past. In this new paradigm, called retroactive data
structures, the historical sequence of operations performed on the
data structure is not fixed. The data structure allows arbitrary insertion
and deletion of operations at arbitrary times, subject only to consistency
requirements.
We initiate the study of retroactive data structures by formally defining
the model and its variants. We prove that, unlike persistence, efficient
retroactivity is not always achievable.
Thus, we present efficient retroactive data structures for queues,
doubly ended queues, priority queues, union-find, and decomposable
search structures.